Classifications

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  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
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  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/04—Liquid carbonaceous fuels essentially based on blends of hydrocarbons
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  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
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  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
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  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/16—Hydrocarbons
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  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/16—Hydrocarbons
  • C10L1/1608—Well defined compounds, e.g. hexane, benzene
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/22—Organic compounds containing nitrogen
  • C10L1/222—Organic compounds containing nitrogen containing at least one carbon-to-nitrogen single bond
  • C10L1/223—Organic compounds containing nitrogen containing at least one carbon-to-nitrogen single bond having at least one amino group bound to an aromatic carbon atom
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  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L10/00—Use of additives to fuels or fires for particular purposes
  • C10L10/10—Use of additives to fuels or fires for particular purposes for improving the octane number
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/182—Organic compounds containing oxygen containing hydroxy groups; Salts thereof
  • C10L1/1822—Organic compounds containing oxygen containing hydroxy groups; Salts thereof hydroxy group directly attached to (cyclo)aliphatic carbon atoms
  • C10L1/1824—Organic compounds containing oxygen containing hydroxy groups; Salts thereof hydroxy group directly attached to (cyclo)aliphatic carbon atoms mono-hydroxy
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  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2200/00—Components of fuel compositions
  • C10L2200/02—Inorganic or organic compounds containing atoms other than C, H or O, e.g. organic compounds containing heteroatoms or metal organic complexes
  • C10L2200/0259—Nitrogen containing compounds
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  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2200/00—Components of fuel compositions
  • C10L2200/04—Organic compounds
  • C10L2200/0407—Specifically defined hydrocarbon fractions as obtained from, e.g. a distillation column
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2200/00—Components of fuel compositions
  • C10L2200/04—Organic compounds
  • C10L2200/0407—Specifically defined hydrocarbon fractions as obtained from, e.g. a distillation column
  • C10L2200/0415—Light distillates, e.g. LPG, naphtha
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2200/00—Components of fuel compositions
  • C10L2200/04—Organic compounds
  • C10L2200/0407—Specifically defined hydrocarbon fractions as obtained from, e.g. a distillation column
  • C10L2200/0415—Light distillates, e.g. LPG, naphtha
  • C10L2200/0423—Gasoline
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2230/00—Function and purpose of a components of a fuel or the composition as a whole
  • C10L2230/22—Function and purpose of a components of a fuel or the composition as a whole for improving fuel economy or fuel efficiency
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2270/00—Specifically adapted fuels
  • C10L2270/02—Specifically adapted fuels for internal combustion engines
  • C10L2270/023—Specifically adapted fuels for internal combustion engines for gasoline engines
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2270/00—Specifically adapted fuels
  • C10L2270/04—Specifically adapted fuels for turbines, planes, power generation

Definitions

• the present invention relates to high octane unleaded aviation gasoline fuel, more particularly to a high octane unleaded aviation gasoline having high aromatics content.
• Avgas aviation gasoline
• mogas motor gasoline
• avgas contains tetraethyl lead (TEL), a non-biodegradable toxic substance used to prevent engine knocking (detonation).
• TEL tetraethyl lead
• Aviation gasoline fuels currently contain the additive tetraethyl lead (TEL), in amounts up to 0.53 mL/L or 0.56 g/L which is the limit allowed by the most widely used aviation gasoline specification 100 Low Lead (100LL).
• TEL tetraethyl lead
• 100LL Low Lead
• the lead is required to meet the high octane demands of aviation piston engines: the 100LL specification ASTM D910 demands a minimum motor octane number (MON) of 99.6, in contrast to the EN 228 specification for European motor gasoline which stipulates a minimum MON of 85 or United States motor gasoline which require unleaded fuel minimum octane rating (R+M)/2 of 87.
• MON motor octane number
• Aviation fuel is a product which has been developed with care and subjected to strict regulations for aeronautical application. Thus aviation fuels must satisfy precise physico-chemical characteristics, defined by international specifications such as ASTM D910 specified by Federal Aviation Administration (FAA). Automotive gasoline is not a fully viable replacement for avgas in many aircraft, because many high-performance and/or turbocharged airplane engines require 100 octane fuel (MON of 99.6) and modifications are necessary in order to use lower-octane fuel. Automotive gasoline can vaporize in fuel lines causing a vapor lock (a bubble in the line) or fuel pump cavitation, starving the engine of fuel.
• MON octane fuel
• Vapor lock typically occurs in fuel systems where a mechanically-driven fuel pump mounted on the engine draws fuel from a tank mounted lower than the pump.
• the reduced pressure in the line can cause the more volatile components in automotive gasoline to flash into vapor, forming bubbles in the fuel line and interrupting fuel flow.
• the ASTM D910 specification does not include all gasoline satisfactory for reciprocating aviation engines, but rather, defines the following specific types of aviation gasoline for civil use: Grade 80; Grade 91; Grade 100; and Grade 100LL. Grade 100 and Grade 100LL are considered High Octane Aviation Gasoline to meet the requirement of modern demanding aviation engines.
• the D910 specification for Avgas have the following requirements: density; distillation; recovery, residue, and loss volume; vapor pressure; freezing point; sulfur content; net heat of combustion; copper strip corrosion; oxidation stability (potential gum and lead precipitate); volume change during water reaction; and electrical conductivity.
• Avgas fuel is typically tested for its properties using ASTM tests:
• an unleaded aviation fuel composition having a MON of at least 99.6, sulfur content of less than 0.05wt%, CHN content of at least 98wt%, less than 2 wt% of oxygen content, an adjusted heat of combustion of at least 43.5 MJ/kg, a vapor pressure in the range of 38 to 49 kPa, freezing point is less than -58 °C comprising:
• the unleaded aviation fuel may contain from 0 vol.% to about 10 vol.% of a co-solvent.
• a high octane unleaded aviation fuel having an aromatics content measured according to ASTM D5134 of from about 35 wt% to about 55 wt% and oxygen content of less than 2wt%, based on the unleaded aviation fuel blend that meets most of the ASTM D910 specification for 100 octane aviation fuel can be produced by a blend comprising from about 35 vol.% to about 55 vol.% of high MON toluene, from about 4 vol.% to about 10 vol.%, preferably from about 5 vol.% to 10 vol.%, of aromatic amine component, the aromatic amine component contains at least about 2 vol.% based on the blend of toluidine, from about 15 vol.% to about 40 vol.%, of at least one alkylate or alkylate blend that have certain composition and properties, and at least about 14 vol.% of isopentane.
• the unleaded aviation fuel may contain from 0 vol.% to about 10 vol.% of a co-solvent.
• a co-solvent may be an alcohol having 4 to 8 carbon atoms, preferably alcohol having 4 carbon atoms if present.
• no ethanol is present in the high octane unleaded aviation fuel composition.
• such co-solvent may be a branched alkyl acetate having branched chain alkyl groups having 4 to 8 carbon atoms.
• the high octane unleaded aviation fuel of the invention has a MON of greater than 99.6.
• the unleaded aviation fuel composition contains less than 1 vol.%, preferably less than 0.5 vol.% of C8 aromatics. It has been found that C8 aromatics such as xylene may have materials compatibility issues, particularly in older aircraft. Further it has been found that unleaded aviation fuel containing C8 aromatics tend to have difficulties meeting certain temperature profile of D910 specification. In one embodiment, the unleaded aviation fuel contains less than 0.2 vol.% of ethers. In another embodiment, the unleaded aviation fuel contains no noncyclic ethers. In another embodiment, the unleaded aviation fuel contains no alcohol boiling less than 80°C. Further, the unleaded aviation fuel composition has a benzene content between 0 vol.% and 5 vol.%, preferably less than 1 vol.%.
• the volume change of the unleaded aviation fuel tested for water reaction is within +/- 2mL as defined in ASTM D1094.
• the high octane unleaded fuel will not contain lead and preferably not contain any other metallic octane boosting lead equivalents.
• the term "unleaded” is understood to contain less than 0.01g/L of lead.
• the high octane unleaded aviation fuel will have a sulfur content of less than 0.05 wt%. In some embodiments, it is preferred to have ash content of less than 0.0132g/L (0.05 g/gallon) (ASTM D-482).
• the NHC should be close to or above 43.5mJ/kg.
• the Net Heat of Combustion value is based on a current low density aviation fuel and does not accurately measure the flight range for higher density aviation fuel. It has been found that for unleaded aviation gasoline that exhibit high densities, the heat of combustion may be adjusted for the higher density of the fuel to more accurately predict the flight range of an aircraft.
• ASTM D910 There are currently three approved ASTM test methods for the determination of the heat of combustion within the ASTM D910 specification. Only the ASTM D4809 method results in an actual determination of this value through combusting the fuel. The other methods (ASTM D4529 and ASTM D3338) are calculations using values from other physical properties. These methods have all been deemed equivalent within the ASTM D910 specification.
• HOC * HOC v / density + % range increase / % payload increase + 1
• HOC * the adjusted Heat of Combustion (MJ/kg)
• HOC v the volumetric energy density (MJ/L) obtained from actual Heat of Combustion measurement
• density is the fuel density (g/L)
• % range increase is the percentage increase in aircraft range compared to 100 LL(HOC LL ) calculated using HOC v and HOC LL for a fixed fuel volume
• % payload increase is the corresponding percentage increase in payload capacity due to the mass of the fuel.
• the adjusted heat of combustion will be at least 43.5MJ/kg, and have a vapor pressure in the range of 38 to 49 kPa.
• the high octane unleaded fuel composition will further have a freezing point of -58°C or less. Unlike for automobile fuels, for aviation fuel, due to the altitude while the plane is in flight, it is important that the fuel does not cause freezing issues in the air. It has been found that for unleaded fuels containing aromatic amines such as Comparative Example D and H in the Examples, it is difficult to meet the freezing point requirement of aviation fuel.
• the final boiling point of the high octane unleaded fuel composition should be less than 210°C, preferably at most 200°C measured with greater than 98.5% recovery as measured using ASTM D-86. If the recovery level is low, the final boiling point may not be effectively measured for the composition (i.e., higher boiling residual still remaining rather than being measured).
• the high octane unleaded aviation fuel composition of the invention have a Carbon, Hydrogen, and Nitrogen content (CHN content) of at least 98wt%, preferably 99wt%, and less than 2wt%, preferably 1wt% or less of oxygen-content.
• the high octane unleaded aviation fuel of the invention not only meets the MON value for 100 octane aviation fuel, but also meets the freeze point, vapor pressure, and adjusted heat of combustion.
• MON it is important to meet the vapor pressure, and minimum adjusted heat of combustion for aircraft engine start up and smooth operation of the plane at higher altitude.
• the potential gum value is less than 6mg/100mL.
• the high octane unleaded aviation fuel of the invention have a T10 of at most 75° C, T40 of at least 75° C, a T50 of at most 105° C, a T90 of at most 135°C.
• US Patent Application Publication 2008/0244963 discloses a lead-free aviation fuel with a MON greater than 100, with major components of the fuel made from avgas and a minor component of at least two compounds from the group of esters of at least one mono- or poly-carboxylic acid and at least one mono-or polyol, anhydrides of at least one mono- or poly carboxylic acid. These oxygenates have a combined level of at least 15%v/v, typical examples of 30%v/v, to meet the MON value.
• Toluene occurs naturally at low levels in crude oil and is usually produced in the processes of making gasoline via a catalytic reformer, in an ethylene cracker or making coke from coal. Final separation, either via distillation or solvent extraction, takes place in one of the many available processes for extraction of the BTX aromatics (benzene, toluene and xylene isomers).
• the toluene used in the invention must be a grade of toluene that have a MON of at least 107 and containing less than 1vol% of C8 aromatics. Further, the toluene components preferably have a benzene content between 0 vol.% and 5 vol.%, preferably less than 1 vol.%.
• an aviation reformate is generally a hydrocarbon cut containing at least 70% by weight, ideally at least 85% by weight of toluene, and it also contains C8 aromatics (15 to 50% by weight ethylbenzene, xylenes) and C9 aromatics (5 to 25% by weight propyl benzene, methyl benzenes and trimethylbenzenes).
• Such reformate has a typical MON value in the range of 102 - 106, and it has been found not suitable for use in the present invention.
• Toluene is preferably present in the blend in an amount from about 35 vol.%, preferably at least about 36 vol.%, most preferably at least about 37 vol.% to at most about 55 vol.%, preferably to at most about 50 vol.%, more preferably to at most about 45 vol.%, based on the unleaded aviation fuel composition.
• Aromatic amine is present in the fuel composition in an amount from about 4 vol.% to about 10 vol.% of aromatic amine component.
• the aromatic amine component contains at least from about 2 vol.% based on the fuel composition of toluidine.
• Toluidine There are three isomers of toluidine (C 7 H 9 N), o-toluidine, m-toluidine, and p-toluidine.
• Toluidine can be obtained from reduction of p-nitrotoluene.
• Toluidine is commercially available from Aldrich Chemical. Pure meta and para isomers are desirable in high octane unleaded avgas as well as combinations with aniline, such as found in aniline oil for red.
• Toluidine is preferably present in the blend in an amount from about 2 vol.%, preferably at least about 3 vol.%, most preferably at least about 4 vol.% to at most about 10 vol.%, preferably to at most about 7 vol.%, more preferably to at most about 6 vol.%, based on the unleaded aviation fuel composition.
• the remainder of the aromatic amine component can be other aromatic amines such as aniline.
• alkylate typically refers to branched-chain paraffin.
• the branched-chain paraffin typically is derived from the reaction of isoparaffin with olefin.
• Various grades of branched chain isoparaffins and mixtures are available. The grade is identified by the range of the number of carbon atoms per molecule, the average molecular weight of the molecules, and the boiling point range of the alkylate. It has been found that a certain cut of alkylate stream and its blend with isoparaffins such as isooctane is desirable to obtain or provide the high octane unleaded aviation fuel of the invention.
• These alkylate or alkylate blend can be obtained by distilling or taking a cut of standard alkylates available in the industry.
• the alkylate or alkyate blend have an initial boiling range of from about 32°C to about 60°C and a final boiling range of from about 105°C to about 140°C, preferably to about 135°C, more preferably to about 130°C, most preferably to about 125°C, having T40 of less than 99°C, preferably at most 98°C, T50 of less than 100°C, T90 of less than 110°C, preferably at most 108°C, the alkylate or alkylate blend comprising isoparaffins from 4 to 9 carbon atoms, about 3-20 vol.% of C5 isoparaffins, based on the alkylate or alkylate blend, about 2-15 vol.% of C7 isoparaffins, based on the alkylate or alkylate blend, and about 60-90 vol.% of C8 isoparaffins, based on the alkylate or alkylate blend, and less than 1 vol.% of C10+,
• Alkylate or alkylate blend is preferably present in the blend in an amount from about 15 vol.%, preferably at least about 17 vol.%, most preferably at least about 22 vol.% to at most about 40 vol.%, preferably to at most about 30 vol.%, more preferably to at most about 25 vol.%.
• Isopentane is present in an amount of at least about 14 vol% in an amount sufficient to reach a vapor pressure in the range of 38 to 49 kPa.
• the alkylate or alkylate blend also contains C5 isoparaffins so this amount will typically vary between 5 vol.% and 25 vol.% depending on the C5 content of the alkylate or alkylate blend.
• Isopentane should be present in an amount to reach a vapor pressure in the range of 38 to 49 kPa to meet aviation standard.
• the total isopentane content in the blend is typically in the range of about 14% to about 26 vol.%, preferably in the range of about 18% to about 25% by volume, based on the aviation fuel composition.
• the unleaded aviation fuel may contain an optional co-solvent.
• the unleaded aviation fuel may contain an alcohol having 4 to 8 carbon atoms, preferably boiling in the range of 80°C to 140°C, preferably an alcohol having a boiling point in the range of 80°C to 140°C and having 4 to 5 carbon numbers, more preferably contains an alcohol having 4 carbon atoms as a co-solvent.
• the unleaded aviation fuel may also contain a branched alkyl acetate having branched chain alkyl group having 4 to 8 carbon atoms as a co-solvent. as a co-solvent in an amount from 0 vol.% to about 10 vol.%.
• the alcohol may be mixtures of such alcohols.
• the alkyl acetate may be mixtures of such branched alkyl acetates. If present, the branched chain alcohol is present in an amount from about 0.1 vol.% to about 10 vol.%, preferably from about 1 vol.% to about 5 vol.%, based on the unleaded aviation fuel.
• Suitable co-solvent may be, for example, iso-butanol, 2-methyl-2-pentanol, 2-methyl-1-butanol, 4- methyl-2-pentanol, and 2-ethyl hexanol.
• Suitable co-solvent may be, for example, t-butyl acetate, iso-butyl acetate, ethylhexylacetate, iso-amyl acetate, and t-butyl amyl acetate.
• the unleaded aviation fuels containing aromatic amines tend to be significantly more polar in nature than traditional aviation gasoline base fuels. As a result, they have poor solubility in the fuels at low temperatures, which can dramatically increase the freeze points of the fuels.
• an aviation gasoline base fuel comprising 10% v/v isopentane, 70% v/v light alkylate and 20% v/v toluene.
• This blend has a MON of around 90 to 93 and a freeze point (ASTM D2386) of less than -76°C.
• the addition of 6% w/w (approximately 4% v/v) of the aromatic amine (aniline) increases the MON to 96.4.
• the freeze point of the resultant blend increases to -12.4°C.
• the current standard specification for aviation gasoline stipulates a maximum freeze point of -58°C. Therefore, simply replacing TEL with a relatively large amount of an alternative aromatic octane booster would not be a viable solution for an unleaded aviation gasoline fuel. It has been found that certain combination of components dramatically decrease the freezing point of the unleaded aviation fuel to meet the current ASTM D910 standard for aviation fuel.
• the water reaction volume change is within +/- 2ml for aviation fuel.
• Water reaction volume change is large for ethanol that makes ethanol not suitable for aviation gasoline.
• the blending can be in any order as long as they are mixed sufficiently. It is preferable to blend the polar components into the toluene, then the non-polar components to complete the blend. For example the aromatic amine and co-solvent are blended into toluene, followed by isopentane and alkylate component (alkylate or alkylate blend).
• the unleaded aviation fuel according to the invention may contain one or more additives which a person skilled in the art may choose to add from standard additives used in aviation fuel.
• additives such as antioxidants, anti-icing agents, antistatic additives, corrosion inhibitors, dyes and their mixtures.
• the aircraft engine is suitably a spark ignition piston-driven engine.
• a piston-driven aircraft engine may for example be of the inline, rotary, V-type, radial or horizontally-opposed type.
• the aviation fuel compositions of the invention were blended in volume % as below. Toluene having 107 MON (from VP Racing Fuels Inc.) was mixed with Toluidine (from Chemsol) while mixing.
• Isooctane from Univar NV
• Narrow Cut Alkylate having the properties shown in Table 1 below (from Shell Nederland Chemie BV) were poured into the mixture in no particular order. Then followed by isopentane (from Matheson Tri-Gas, Inc.) to complete the blend.
• Alkylate Blend Properties IBP (ASTM D86, °C) 68.1 FBP (ASTM D86, °C) 110.8 T40 (ASTM D86, °C) 98.1 T50 (ASTM D86, °C) 98.7 T90 (ASTM D86, °C) 100.9 Vol.% iso-C5 3.74 Vol.% iso-C7 2.47 Vol.% iso-C8 87.33 Vol.% C10+ 0.006
• Blend X4 and Blend X7 The properties of a high octane unleaded aviation gasoline that use large amounts of oxygenated materials as described in US Patent Application Publication 2008/0244963 as Blend X4 and Blend X7 is provided.
• the reformate contained 14 vol.% benzene, 39 vol.% toluene and 47 vol.% xylene.
• a high octane unleaded aviation gasoline that use large amounts of mesitylene as described as Swift 702 in US Patent No. 8313540 is provided as Comparative Example C.
• a high octane unleaded gasoline as described in Example 5 of US Patent Application Publication Nos. US20080134571 and US20120080000 are provided as Comparative Example D.

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